Generalized spin-squeezing inequalities for particle number with quantum fluctuations

Saideh, Ibrahim; Felicetti, Simone; Coudreau, Thomas; Milman, P.

doi:10.1103/physreva.94.032312

Cited by 5 publications

(7 citation statements)

References 28 publications

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“…In this contribution, a coarse graining map will simply be a CPTP linear map that reduces the dimension of the system. Such maps were recently used to obtain a sufficient criteria for the entanglement of high-dimensional bipartite states [24]. After that, in Section III, we obtain the effective dynamics Γ t induced by the coarse graining Λ CG , underlying evolution U t , and initial state ψ 0 .…”

Section: Description Of the Systems?mentioning

confidence: 99%

“…Physically this constraint comes from the fact that if one does not have control of all the degrees of freedom of a system, then not all the states can be generated. In another perspective, the entanglement that can be created in the fundamental level H A ⊗ H D is, in general, decreased by the action of the coarse graining map [24].…”

Section: Properties Of γ Tmentioning

confidence: 99%

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Emerging dynamics arising from coarse-grained quantum systems

et al. 2017

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The purpose of physics is to describe nature from elementary particles all the way up to cosmological objects like cluster of galaxies and black holes. Although a unified description for all this spectrum of events is desirable, an one-theory-fits-all would be highly impractical. To not get lost in unnecessary details, effective descriptions are mandatory. Here we analyze what are the dynamics that may emerge from a full quantum description when one does not have access to all the degrees of freedom of a system. More concretely, we describe the properties of the dynamics that arise from quantum mechanics if one has only access to a coarse grained description of the system. We obtain that the effective maps are not necessarily of Kraus form, due to correlations between accessible and non-accessible degrees of freedom, and that the distance between two effective states may increase under the action of the effective map. We expect our framework to be useful for addressing questions such as the thermalization of closed quantum systems, as well as the description of measurements in quantum mechanics.

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Section: Description Of the Systems?mentioning

confidence: 99%

Section: Properties Of γ Tmentioning

confidence: 99%

Emerging dynamics arising from coarse-grained quantum systems

et al. 2017

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“…We show that, in this limit, the superradiant phase transition of the twophoton DM entails squeezing and spin-squeezing properties. These features provide a signature of the phase transition that could be observed [50][51][52] for a smaller number of qubits.…”

Section: Introductionmentioning

confidence: 99%

Superradiant phase transition in the ultrastrong-coupling regime of the two-photon Dicke model

et al. 2017

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The controllability of current quantum technologies allows to implement spin-boson models where two-photon couplings are the dominating terms of light-matter interaction. In this case, when the coupling strength becomes comparable with the characteristic frequencies, a spectral collapse can take place, i.e. the discrete system spectrum can collapse into a continuous band. Here, we analyze the thermodynamic limit of the two-photon Dicke model, which describes the interaction of an ensemble of qubits with a single bosonic mode. We find that there exists a parameter regime where two-photon interactions induce a superradiant phase transition, before the spectral collapse occurs. Furthermore, we extend the mean-field analysis by considering second-order quantum fluctuations terms, in order to analyze the low-energy spectrum and compare the critical behavior with the one-photon case.

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“…[6]. Recently there are many studies on inequalities of spin squeezing [7][8][9][10], which are progressively used to establish mathematical criteria to detect entanglement and negative pairwise correlations in quantum systems. Most importantly spin squeezing is a good tool to study the quantum correlations in quantum ensembles, where constitutes of the system cannot be addressed individually and collective behavior of the system play the significant role, like in Bose-Einstein condensate.…”

Section: Introductionmentioning

confidence: 99%

Decoherence assisted spin squeezing generation in superposition of tripartite GHZ and W states

Sharma¹,

Ganguly²

2019

EPJ Web Conf.

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In the present paper, we study spin squeezing under decoherence in the superposition of tripartite maximally entangled GHZ and W states. Here we use amplitude damping, phase damping and depolarisation channel. We have investigated the dynamics of spin squeezing with the interplay of superposition and decoherence parameters with different directions of the mean spin vector. We have found the mixture of GHZ and W states is robust against spin squeezing generation for amplitude damping and phase damping channels for certain directions of the mean spin vector. However, the depolarisation channel performs well for spin squeezing generation and generates permanent spin squeezing in the superposition of GHZ and W states.

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Generalized spin-squeezing inequalities for particle number with quantum fluctuations

Cited by 5 publications

References 28 publications

Emerging dynamics arising from coarse-grained quantum systems

Emerging dynamics arising from coarse-grained quantum systems

Superradiant phase transition in the ultrastrong-coupling regime of the two-photon Dicke model

Decoherence assisted spin squeezing generation in superposition of tripartite GHZ and W states

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